I. Field of the Invention
This invention relates to a newly developed sprayer and method for spraying powdered material in an extremely small quantity activated by pulsating vibration air, and more particularly to a sprayer for spraying bulky and soft powdered material with large specific volume or powdered material with poor fluidity without causing clogging.
II. Prior Art
Manufacturing of tablets is generally comprised of a weight, mixing, granulation, tableting and inspection process. A trace of an additive, which is described in a statement of the powers of medicine, is added to the basis of the medicine in the process of mixing or tableting.
A sprayer for effectively spraying powdered material in extremely small quantities has been disclosed in Japanese Patent Application H6-10187 (filed on Feb. 1, 1994).
This sprayer as shown in FIG. 7, is provided with a storage tank a with a valve f at the bottom end in which powdered material h is stored. The sprayer is also provided with a reservoir c which has a body for storing the powdered material h, a filter cloth b formed with at least plural bores g at the tip end, and a gas feeding means d.
According to the sprayer so constructed, powdered material h can be continuously sprayed through the bores g when the filter cloth b of the reservoir c is forcedly vibrated by a vibrator e while driving gas is fed into a communication pipe i from the gas feeding means d.
However in such a sprayer, bulky and soft powdered material with a large specific volume, in which the ratio of air to powder is rather large, or a powdered material with poor fluidity, cannot be sprayed for a long period without causing clogging since such powdered material stored in the reservoir c would be caught in the bores g of the filter cloth b while the sprayer is repeatedly used. Namely, clogging has often been caused in such a sprayer. Further, considerable time is needed in that the powdered material thus attached to the filter cloth b amounts to a constant quantity, and sprayer amount per unit time becomes constant.